Glue



1 2,784,106 GLUE,

Moss B. Christian and Horace F. Ladd, Tallulah, La.,

assignors to Chicago Mill & Lumber Company, Chicago, Ill., a corporationof Illinois No Drawing. Application February 21, 1955 Serial No. 489,7726 Claims. (Cl. 166-154) The present invention is directed to improvedglue compositions and is particularly directed to glue compositionsadapted to secure paper sheets on wet and swollen wood veneer panels.

While the glue composition of the present invention has generalapplicability, it finds particular use in the preparation ofpaper-covered wood veneer in which the paper is applied to the veneerwhile the latter is in a wet, swollen condition. Briefly, this type ofprocess includes the steps of peeling or cutting undried green Wood inthe conventional manner to form veneer sheets of the desired thickness,after which the veneer sheets are con nected together to form acontinuous ribbon. A tough, water absorbent paper such as unsized kraftpaper is unreeled from rolls which are positioned above and below thecontinuous ribbon of veneer. Suitable coating machines apply a glue toone face of each of the paper sheets from the rolls, and the glue coatedfaces of the paper are then deposited on the veneer ribbon as itadvances. Pressure rolls are provided to squeeze the paper firmlyagainst the wood so that intimate contact between the wood and the gluecoated faces of the paper is insured. If the characteristics of the glueare as required, the glue will bond the paper to the wood before thewood is dried to a point where shrinkage can occur. After the bond hasbeen formed between the paper and the veneer, the paper covered veneeris dried so that the paper and wood simultaneously loose their moisture.During the drying operation, the paper, holds the Wood in its expanded,swollen condition even after the wood loses most of its moisture. Sincewood does not begin to shrink until its moisture content is reducedbelow about it is necessary that a glue bond be formed while themoisture content of the wood is still above that value.

For reasons of availability and economy, it would be desirable to usealkalinized proteinaceous vegetable flour glues, such as soya beanglues, locust bean glues, cotton seed glue, linseed glue, and the likefor this bonding action. However, such materials are very deficient whenutilized on wet materials in appreciable amounts. This deficiency isparticularly marked in the process outlined previously because asatisfactory glue for the above described process must be capable offorming a strong States Patent bond at relatively high moisturecontents, it must not a be efiected adversely by the passage of steamthrough the glue as the paper covered veneer is heated to drive off themoisture, and it must not become brittle either during the dryingprocess or upon setting. In addition to the foregoing, the glue mustretain its free flowing characteristics for a substantial period of timeand must be capable of being mixed and applied without the presence offoam or air bubbles.

Accordingly, an object of the present invention is to provide a gluecomposition from seed protein material which has sufficient water andsteam resistance to be useful in securing continuous webs of paper to aWet, swollen wood veneer.

Another object of the invention is to provide an improved compositionwhich has excellent flow characteristics, and which retains thosecharacteristics for sub stantial periods of time.

Another object of the invention is to provide an'ima 2,784,106 a l-"a'tentecl'lvlar. 5. 5

Another object of this invention is to provide a soy' bean gluecomposition which not only has improved properties compared to soy beancompositions of the past, but can be compounded at a lower cost.

The glue composition of the present invention contains a vegetable beanprotein such as soya flour as its essential ingredient, and sufficientalkali to put the soya flour in suspension in water, and to develop itsadhesive properties. In addition, the adhesive composition containssodium silicate and lime. Preferably, although not necessarily, thecomposition may also include a preservative to control molds, stains,and similar bacterial growth.

- One of the features of the present invention resides in the inclusion,in glue compositions, of a mixture of a phenolic compound and apetroleum distillate. The phenolic compound may be a material such ascresylic acid (a mixture of the three isomeric cresols), or it may bephenol, or coal tar distillates containing substantial amounts ofhydroxy substituted aromatic compounds.

In the glue composition of the present invention, the phenolic compoundreplaces the mixture of carbon bisulphide and carbon tetrachloride whichhas been previously added in many glue compositions of this type. It hasbeen found that the substitution of the phenolic compound for the carbonbisulphide-tetrachloride solution increases the adhesive life ofv theglue remarkably, usually on the order of about four times. Furthermore,when used in combination with the petroleum distillate, the phenoliccompound provides a much smoother consistency to the glue, resulting ina better physical mixfree foam or air bubbles. The employment of thepetroleum hydrocarbon has been found to permit the use of smalleramounts of water in the glue formula, resulting in a tacky adhesivewithout excessive viscosity. The reduction in the amount of water isadvantageous because it decreases the amount of time required to set theglue. In addition, the presence of the petroleum distillate apparentlyreduces the expansion of the paper which Was previously troublesomebecause in. wide widths, glue compositions without the petroleumdistillate would sometime cause wrinkling of the paper. The combinationof the petroleum distillate and the phenolic com.- pound also maintainsthe glue viscosity at a constant level over a longer period oftime.Heretofore, trouble has been experienced in soya bean. glues becausethey tend to increases in viscosity very. rapidly and, after thickening,to become thin and lacking in adhesiveness.

The elimination of the carbon bisulphide as an ingredient of thecomposition has the further advantage that it eliminates the problems ofhandling and storing a compound which, due to its low flash point,presents a definite fire hazard.

In addition to the foregoing ingredients, the improved glue compositionof the present invention also preferably includes a residual resin fromwood which is substantially freed of wood rosin. The resin, unlike woodrosin, is substantially insoluble in light petroleum hydrocarbons suchas gasoline. A particularly suitable resin is known under the trade nameVinsol and has a melting point by the drop method of C., an acid numberof about 93, and a methoxyl content of about, 3 to 6%. it is obtained byextracting southern long-leaf pine wood with a coal tar hydrocarbon toproduce a coal tar hydrocarbon extract containing turpentine, pine oil,rosin, and a residue. I Volatiles are removed from the extract byevaporation, and rosin is then separated from the residue by extractionwith gasoline.

The gasoline-insoluble residual material is the material which has beenreferred to in this specification and claims as a gasoline insolubleresin from southern long-leaf pine.

In compounding the adhesive composition of the present invention, 'weprefer to addthe petroleum distillate early in the compounding of themixture, because it has been found the presence of distillate aids indispersing the remainder of the ingredients. While various petroleumdistillates can be employed for the purpose of the invention, we preferto employ a kerosene fraction boiling between about 150 C. and 300 C.,and having a specific gravity of about 0.80 to 0.85.

Based upon a soya flour content of 200 lbs., the composition of thepresent invention contains the following ingredients in the followingproportions:

2 to 30 lbs. of lime 4 to 20 lbs. sodium hydroxide to 40 lbs. ofgasoline insoluble resin from southern long-leaf pine to 40 lbs. ofsodium silicate .05 to 2 lbs. of a phenolic compound 1 to 15 quarts ofpetroleum distillate Expressed in terms of parts by weight, thecomposition becomes:

Petroleum distillate 1.66 to 25 The solids listed above are combinedWith sufiicient water to make a dispersion having a solids content fromabout to 50% by weight.

In order to aid in dispersing the phenolic compound in the aqueousmixture, we prefer to add the compound in the form of pre-emulsifiedcomposition containing small amounts of an alcohol, alkali, and otherdispersing agents.

The following is a specific example of the method employed in thecompounding of the glue in the present invention.

About 525 lbs. of water at a temperature of about 80 to 90 F., whereintroduced into a mixer, followed by the addition of 10 quarts ofkerosene. About 200 lbs. of soya flour were blended with 20 lbs. Vinsolresin and this blend was added to the mixture and agitated until all thelumps disappeared, and a smooth physical mixture was obtained. Next, 26lbs. of lime having a particle size of about 400 mesh were mixed in 50lbs. of water at a temperature of 180 to 212 F. After thoroughagitation, the hot, slaked lime was added to the mixer. About 13 lbs. ofsodium hydroxide in flake form were dissolved in lbs. of water at roomtemperature. This mixture was agitated until the caustic was dissolved,and then added to the mixer.

Next, 6 lbs. of a preservative, Dowicide A (sodium ortho-phenyl phenate)plus 1 lb. of sodium hydroxide were dissolved in 20 lbs. of water at atemperature of 180 to 212 F. After the solids were completely dissolved,the solution was added to the mixer.

Next, 30 lbs. of sodium silicate was added to the mixer. The mixer wasthen agitated for three to five minutes.

Finally, a cresol composition was added in an amount of ,4 lb. of thecresol composition in 2 lbs. of water. The cresol composition containedabout 52% cresylic acid, 32% fatty acids, 4 /z% isopropyl alcohol, 4 /z%caustic soda, 3% glycerine, and 4% water. After thorough agitation, thissolution was added to the mixer.

The glue which resulted was smooth flowing, and free from foam orentrained air bubbles. It maintained the desired flow viscosity forextendedperiods of time, and exhibited a strong bond between the paperand the wood veneer.

While the glue of the present invention has been described primarily inconnection with processes for securing paper to wood, the glue heredescribed also makes a superior glue for the manufacture of plywood andother general uses.

It will be evident that various modifications can be made to thedescribed embodiments without departing from the scope of the presentinvention.

W e claim as our invention:

1. A glue composition particularly adapted to bond paper to wood veneerconsisting essentially of an aqueous dispersion of soya bean flourcontaining, for every 200 lbs. of soya bean flour, from 2 to 30 lbs. oflime, from 4 to 20'lbs. of sodium hydroxide, from 10 to 40 lbs. of agasoline insoluble resin from southern long-leaf pine, from 15 to 40lbs. of sodium silicate, from .05 to 2 lbs. of a phenolic compoundselected from the group consisting of phenols and cresols, and from 1 to15 quarts of a petroleum distillate.

2. A glue composition particularly adapted to bond paper to wood veneerconsisting essentially of an aqueous dispersion of soya bean flourcontaining, for every 200 lbs. of soya bean dorm-from 2 to 30 lbs. oflime, from 4 to 20 lbs. of sodium hydroxide, from -10 to 40 lbs. of agasoline insoluble resin from southern long-leaf pine, from 15 to 40lbs. of sodium silicate,- from .05 to 2 lbs. of a phenolic compoundselected from the group consisting of phenols and cresols, and from 1 to15 quarts of kerosene.

3. A glue composition particularly adapted to bond paper to Wood veneerconsisting-essentially of an aqueous dispersion of soya bean' flourcontaining, for every 200 lbs. of soya bean flour, from 2 to 30 lbs. oflime, from 4 to 20 lbs. of sodium hydroxide, from 10 to 40 lbs. of agasoline insoluble resin from southern long-leaf pine, from 15 to 40lbs. of sodium silicate, from .05 to 2 lbs. of cresylic acid, and from 1to 15 quarts of a petroleum distillate.

4. A glue composition particularly adapted to bond paper to wood veneerconsisting essentially of an aqueous dispersion of soya bean fiourcontaining, for every 200 lbs. of soya bean flour, from 2 to 30 lbs. oflime, from 4 to 20 lbs. of sodium hydroxide, from 10 to 40 lbs. of agasoline insoluble resin fromsouthern long-leaf pine, from 15 to 40 lbs.of sodium silicate, from .05 to 2 lbs. of cresylic acid, and from 1 to15 quarts of kerosene.

5. A glue composition particularly adapted to bond paper to wood veneerconsisting essentially of an aqueous dispersion of soya bean flourcontaining, for every 200 lbs. of soya bean flour, from 2 to 30 lbs. oflime, from 4 to 20 lbs. of sodium hydroxide, from 10 to 40 lbs. of agasoline insoluble resin from southern long-leaf pine, from 15 to 40lbs. of sodium silicate, from .05 to 2 lbs. of a phenolic compoundselected from the group consist-v ing of phenols and cresols, and from 1to 15 quarts of a petroleum distillate, said dispersion having a solidscontent of from 20 to 50% by weight.

6. A glue composition particularly adapted to bond paper to wood veneerconsisting essentially of an aqueous dispersion of soya bean flourcontaining, for every 200 lbs; of soya bean flour, from 2 to 30 lbs. oflime, from 4 to 20 lbs. of sodium hydroxide, from 10 to 40 lbs. of agasoline insoluble resin from southern long-leaf pine, from 15 to 40lbs. of sodium silicate, from .65 to 2 lbs. of cresylic acid, and from 1to 15 quarts of kerosene, said dispersion having a solids content offrom 20 to 50% by Weight.

References Cited in the file of this patent UNITED STATES PATENTS1,833,772 Bradshaw Nov. 24, 1931 2,206,369 Salzberg July 2, 19402,494,744 Christian Jan. 17, 1950 2,527,643 Morison Oct. 31, 1950

6. A GLUE COMPOSITION PARTICULARLY ADAPTED TO BOND PAPER TO WOOD VENEERCONSISTING ESSENTIALLY OF AN AQUEOUS DISPERSION OF SOYA BEAN FLOURCONTAINING, FOR EVERY 200 LBS. OF SOYA BEAN FLOUR, FROM 2 TO 30 LBS, OFLIME, FROM 4 TO 20 LBS. OF SODIUM HYDROXIDE, FROM 10 TO 40 LBS. OF AGASOLINE INSOLUBLE RESIN FROM SOUTHER LONG-LEAF PINE, FROM 15 TO 40 LBS.OF SODIUM SILICATE, FROM .05 TO 2 LBS. OF CRESYLIC ACID, AND FROM 1 TO15 QUARTS OF KEROSENE, SAID DISPERSION HAVING A SOLIDS CONTENT OF FROM20 TO 50% BY WEIGHT.